Lentidium mediterraneum
Habitat: it lives in the littoral zone either on sandy or sandy-muddy bottoms, even near the rivers estuaries. Distribution: common all over the Mediterranean. In plenty, locally. It is present in the Black Sea too.
Notes: shell very changeable in its outline, in its solidity and in its colour pattern, brittle, elliptical in form, inequivalve, umbo placed centrally. The characteristic, making this species easily distinguishable, is the left valve which is smaller and it is contained into the right valve which is protuberant in the posterior part and in the ventral zone. From umbo it starts a sort of carina reaching the posterior margin resulting more angular. Anterior margin roundish. Teeth of hinge can be so developed that sometimes they overcome the dorsal margin of valves. Either dirty white or yellowish in ground colour, either with bands or stains brown. Periostracum light brown non persistent.
Juvenile forms are more roundish in outline, but, mainly in the ventral zone, the right valve, which is protuberant, is quite clear. In confirmation of the intraspecific variability of this species, there can be found a lot of varieties in literature: minor, decurtata, solidula, cornea, fulva, alba, ochracea, citrina, sulphurea, balaustina fulvoradiata, incarnatum, maeoticum, all of them of no taxonomic value. The other Mediterranean species belonging to the Family Corbulidae, that is Corbula gibba, is easily recognizable since it is more roundish in outline and for its bigger solidity. Moreover it is clearly more inequivalve, it has a different colour pattern, a clearer periostracum and a deeper habitat.